A potentially important, but inadequately studied, source of passengers' exposure to pollutants when a road vehicle is stationary, with an idling engine, results from the ingestion of a vehicle's own exhaust into the passenger compartment through the HVAC intake. We developed and applied a method to determine the fraction of a vehicle's exhaust entering the cabin by this route. Further the influence of three parameters: ambient tail-wind speed, vehicle ground clearance and tail pipe angle, is assessed. The study applies Computational Fluid Dynamic (CFD) simulation to the distribution of exhaust gasses around a vehicle motorized with a 2.2 liter Diesel engine. The simulation employs efficient meshing techniques and realistic loading conditions to develop a general knowledge of the distribution of the gasses in order to inform engineering design. The results show that increasing tail-wind velocity, tail-pipe angle and ground clearance reduces the presence of CO and NO at the HVAC intake. The trends for NO2 are not predicted to follow the same pattern.
Abo-Serie, E. F., Sherif, M., Pompei, D., & Gaylard, A. (2014). CFD Simulation of external distribution of tail-pipe emissions around a stationary vehicle under light tail-wind conditions. SAE Technical Papers, 1, [2014-01-0586]. https://doi.org/10.4271/2014-01-0586